There has be more to it than low batts. I can kill my house batts (deep cycle) and have to start coach just so the batts will start to take a charge. As soon as 12v comes back on I shut down coach and the inverter will bring batts back up. I believe we have the same inverter and I believe yours is fubar.
2004 40' Winnebago Vectra towing a 2006 Saturn Vue